AUGUSTA, Ga. – Jordan Spieth was all of 3 years old in April 1997, when Tiger Woods unleashed his historic assault on Augusta National. Now, at the ripe old age of 20, Spieth is threatening to remove Woods from at least one section of the Masters record book.

Spieth planted himself in great position Saturday – to become the youngest champion in tournament history and also to become the first Masters rookie to win since Fuzzy Zoeller in 1979. All the conventional logic about needing years of experience to conquer Augusta National suddenly doesn’t seem all that relevant.

“He’s always had an inner calmness you really don’t see in 20-year-olds,” said Mike Greller, Spieth’s 36-year-old caddie.

Jordan Spieth’s poise, and steady putting, lifted him into a tie for the lead with Bubba Watson. (Getty photo)

Spieth shot 2-under-par 70 in Saturday’s third round, another steady-as-she-goes effort after he posted 71 on Thursday and 70 on Friday. This latest display of preternatural poise pushed him to 5-under-par for the tournament, tied with Bubba Watson (74) for the lead in golf’s first major championship of the year.

Matt Kuchar and Jonas Blixt will begin Sunday’s final round one stroke back, at 4-under, with Rickie Fowler and Miguel Angel Jimenez at 3-under.

Spieth played his way into Sunday’s final pairing alongside Watson, the long-hitting 2012 Masters winner. Watson will no doubt launch his tee shots well past Spieth’s in the final round – but don’t expect that to unnerve the young Texan.

“I can take a lot of confidence out of today,” Spieth said after Saturday’s round. “I wanted to get in contention to see how I could perform on Sunday. Tomorrow is about seeing how I can control my emotions and my game on this course.”

Or, as Greller said, “It feels like we’re playing with house money. Maybe we’re too dumb to know what we’re doing.”

Spieth started his day by hitting a wayward tee shot on No. 1 – so wildly left that it cleared the tree line, bounced off a sprinkler head, went through the No. 9 fairway and ended up on No. 8. That gave him a clear if unconventional path to the green, leading to a routine tap-in par. Ho hum.

His body language belies his age, calling to mind the old Walter Payton line about scoring a touchdown: Act like you’ve been to the end zone before and expect to return. That’s why Payton flipped the ball to the referee and moved along.

Spieth, similarly, offered only a brief, barely noticeable fist pump – actually more of a fist jab – when he rolled home an 8-foot birdie putt on No. 6. That lifted him into sole possession of second place, three shots behind Watson.

From there, Spieth kept pecking away. He did nothing spectacular but also nothing stupid, avoiding the kind of train-wreck holes to derail players with far more experience at majors. Spieth dropped a stroke at No. 11 – and soon came back with consecutive birdies at Nos. 14 and 15.

Watson, meantime, fought himself most of the afternoon. His personal history suggested discomfort playing with the lead; Watson is 1-for-7 when holding the 54-hole lead on the PGA Tour.